Abstract: In Ni-base superalloys with low Al and/or Ti content the precipitation and
subsequent coarsening of gamma' particles at intermediate temperatures
contribute to the degradation of the mechanical properties of the alloy. In the
present paper the coarsening process is modelled and the change of the critical
resolved shear stress of the alloy due to coarsening of the gamma' particles is
calculated by means of statistical analysis of the depinning of a single
gliding edge dislocation. It is found that the contribution of gamma' hardening
to the critical resolved shear stress at 973 K reduces to more than half of its
original value in less than one year.